Mobile voice-over-IP (VoIP) handover is the process of continuing a voice call as a user moves between IP-based networks (e.g., wireless LAN (WLAN) or Wi-MAX networks, etc.) and circuit-switched cellular networks. To effectuate such handover, current 3rd Generation Partnership Project (3GPP) standards specify that when a dual mode wireless device originates a call requiring inter-domain continuity, the call be routed to a call continuity control function (CCCF) element that is disposed in a new, IP-based network architecture referred to as the IP multimedia subsystem (IMS). One of the proposed solutions to implement the call routing process involves providing a Public Service Identity in the form of an E.164 number (e.g., a called party number) to which a call reference identity may be appended to generate an IP multimedia routing number (IMRN). However, when call reference identity digits are appended to the E.164 number, it results in a number that is longer than the 15-digit length limitation specified under the ITU-T standards. It is therefore possible that the extra digits may be lost when such a number is routed via a network. Further, if there is a reliance on the Caller ID information being provided to the CCCF element in the IMS network, this information may be lost in the international ISDN infrastructure using the ISDN User Part (ISUP) signaling.